Can Amiodarone (antiarrhythmic medication) cause myocardial infarction?

Amiodarone and Myocardial Infarction Risk

Amiodarone does not cause myocardial infarction, but it can cause hypotension which may potentially worsen ischemia in patients with coronary artery disease. 1

Cardiovascular Effects of Amiodarone

• Amiodarone has multiple actions including potassium and sodium channel blockade, antiadrenergic effects, and coronary vasodilation 2
• The drug has a favorable safety profile regarding its effects on the electrophysiological substrate and cardiac pump function 2
• Amiodarone can actually reduce the risk of re-infarction in post-MI patients 2
• While amiodarone commonly causes QT prolongation, it rarely causes torsades de pointes or ventricular proarrhythmia (<2% of cases) 1, 3

Hemodynamic Effects and Potential Concerns

• The most common adverse cardiovascular effect of amiodarone is hypotension, reported in 16% of patients receiving IV amiodarone 1
• Hypotension is most often seen in the first several hours of treatment and appears related to the rate of infusion rather than dose 1
• In rare cases, hypotension may be refractory and result in fatal outcomes 1
• Bradycardia and AV block can occur in 4.9% of patients receiving amiodarone 1

Clinical Evidence on Mortality and MI Risk

• Multiple randomized trials have shown that amiodarone has no or little effect on all-cause mortality in post-MI patients 2, 4
• Amiodarone provides substantial (about 30%) protection against sudden cardiac death, but this benefit is counterbalanced by a drug-related increase in non-sudden death rate 2
• The European Myocardial Infarct Amiodarone Trial (EMIAT) found a 35% risk reduction in arrhythmic deaths but no difference in all-cause mortality or cardiac mortality in post-MI patients with reduced ejection fraction 4
• Amiodarone may be considered for relief of symptoms from ventricular arrhythmias in survivors of myocardial infarction, but it has no effect on mortality (Class IIb recommendation, Level B evidence) 2

Guidelines for Use

• Amiodarone is approved for use in the secondary prevention of life-threatening ventricular arrhythmias 2, 5
• It is not recommended for primary prevention of sudden death as implantable cardioverter-defibrillators (ICDs) are more effective 2, 5
• Amiodarone can be used as an adjunct to reduce the frequency of ICD shocks or to control atrial fibrillation in selected highly symptomatic patients 2, 5
• For symptomatic but not life-threatening arrhythmias (PVCs or short and slow NSVT), amiodarone is the drug of choice since it suppresses arrhythmias without worsening prognosis 2

Monitoring and Precautions

• Patients receiving amiodarone should be monitored for QTc prolongation during infusion 1
• Combination of amiodarone with other antiarrhythmic therapy that prolongs the QTc should be reserved for patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent 1
• Careful assessment of potential risks and benefits must be made in patients with thyroid dysfunction due to the possibility of arrhythmia breakthrough or exacerbation 1
• Regular monitoring of thyroid function, liver function, and pulmonary function is essential 5

Conclusion

While amiodarone does not directly cause myocardial infarction, its hemodynamic effects (particularly hypotension) require careful monitoring, especially in patients with coronary artery disease. The drug actually shows some protective effects against reinfarction and arrhythmic death, though it does not improve overall mortality.